1. Technical Field
The present invention concerns a developing unit provided in an electrophotographic apparatus, such as a laser beam printer, an electronic copier, an ordinary paper facsimile or a versatile office machine, and more particularly, a process and toner supply roll for supplying toner to the developing roll in such an electrophotographic apparatus.
2. Related Art
In the conventional developing apparatus, a toner tank stores toner, and a blade is provided for supplying toner from the toner tank to a developing roll. Typically, the blade for supplying toner to the developing roll is a simple blade having at least two branches. Such an arrangement is disclosed, for example, in U.S. Pat. No. 5,338,895 of Ikegawa et al., entitled Developing Apparatus.
A similar arrangement is disclosed in U.S. Pat. No. 5,243,390 of Takamoto et al., entitled Device For Conveying Developer In A Developing Device. The latter patent discloses a rotating member 12 for supplying toner to a developing roll, the rotating member 12 having a channel member located at its outer end, the channel member being somewhat tapered.
Other arrangements which are of general background interest are disclosed in the following patents: U.S. Pat. No. 5,319,461 to Lindblad et al., entitled Apparatus For Increased Toner Storage Capacity, U.S. Pat. No. 5,315,357 to Kamijo et al., entitled Cleaning Unit Provided In Xerographic Image Forming Apparatus For Removing Residual Toner From An Image Carrier, U.S. Pat. No. 5,081,505 to Ziegelmuller et al., entitled Cleaning Apparatus Having Indexable Wiper Blades, U.S. Pat. No. 4,992,834 to Yamamoto et al., entitled Cleaning Blade Arrangement For Image Forming Apparatus, U.S. Pat. No. 4,619,523 to Maeda et al., entitled Toner Cleaning Apparatus In Electrophotography, U.S. Pat. No. 4,566,776 to Kondoh, entitled Magnetic Toner Developing Device, U.S. Pat. No. 4,561,766 to Fox, entitled Blade Cleaner Apparatus For Removing Toner From A Charge-Retentive Surface, and U.S. Pat. No. 4,119,060 to Mochizuki et al., entitled Toner Charging Apparatus.
I have found that each of these arrangements is disadvantageously burdened by the fact that only a small portion of the toner is supplied to the developing roll. That is to say, the force provided by such rotating blades is too weak to supply a sufficient amount of toner to the developing roll as the blade rotates. Thus, printing quality of the developing roll is below acceptable standards.
I have also found that, in some conventional designs, because both sides of each branch of the blade of the toner supply roll are parallel to each other, the force required to push the toner toward the developing roll is insufficient to continuously supply a sufficient amount of toner to the developing roll. Consequently, I have noticed that not only does this deficiency lower the printing quality of the developing roll, but it also increases the amount of toner remaining in the toner receptacle.